Alarm apparatus utilizing high frequency

Claim 2

An alarm system utilizing electromagnetic waves for detecting a moving object, comprising, in combination: at least one antenna means; at least one transmitter-receiver apparatus having an oscillation loop for detecting changes in the impedance of said antenna means; an amplifier circuit is operatively connected to said transmitter-receiver apparatus for amplifying an output signal from said transmitter-receiving apparatus; an alarm device operatively connected to said amplifier circuit is operated by the amplified signal so that an alarm is produced in response to said object moving in the range of space covered by the electromagnetic waves rediated radiated said antenna means; and a first timing device and a second timing device disposed between said amplifier circuit and said alarm device, said second timing device being operated when said first timing device is operated, and a charge-discharge circuit is disposed so that said second timing device stays in its operating state for a certain definite time even after said first timing device is changed over from its ON to OFF state.

Claim 3

An alarm system as defined in claim 1, wherein a plurality of said transmitter-receiver apparatus are centrally connected to said amplifier circuit, and said alarm device is operated when the antenna impedance is changed in any one of said transmitter-receiver apparatus, and thus an object moving in a wide range of space is alarmed.

Claim 4

An alarm system as defined in claim 2, including a plurality of video cameras which are operatively connected to and respectively associated with predetermined ones of said plurality of transmitter-receiver apparatus so that said object moving in the space covered by each transmitter-receiver apparatus is monitored and/or recorded by the individual monitors and/or video tape recorders operatively connected to said video cameras.

Claim 5

An alarm system as defined in claim 1, wherein said transmitter-receiver apparatus includes an oscillation circuit; a lead wire is connected into the loop of said oscillation circuit including the antenna; an oscillating current is supplied thereto through said lead wire; and said object moving in an electrostatic electric field produced around said lead wire is detected in terms of a change in the antenna impedance.

Claim 6

An alarm system as defined in claim 1, including a video camera operable in response to changes in the antenna impedance of said transmitter-receiver apparatus, and a monitor and/or a video tape recorder connected to said video camera, and said object moving in the space of said electromagnetic waves is displayed on said monitor and/or recorded on said video tape recorder.

Claim 7

An alarm system as defined in claim 1, including a bandpass filer disposed in said amplifier circuit for removing high frequency componentS such as hum noise.

Claim 8

An alarm system utilizing electromagnetic waves for detecting a moving object, comprising, in combination: at least one antenna means; at least one transmitter-receiver apparatus having an oscillation loop for detecting changes in the impedance of said antenna means; an amplifier circuit is operatively connected to said transmitter-receiver apparatus for amplifying an output signal from said transmitter-receiver apparatus; an alarm device operatively connected to said amplifier circuit is operated by the amplified signal so that an alarm is produced in response to said object moving in the range of space covered by the electromagnetic waves radiated from said antenna means; a timing device disposed between said amplifier circuit and said alarm device; said alarm device is operated only when the intensity and the timing of the received signal and said transmitter-receiver apparatus exceeds their specific predetermined values; and wherein said timing device includes: a transistor, a diode connected between the base of said transistor and the power source, and a lead wire connected between said power source and the ground so that the current to flow in the base of said transistor is normally cut off; and said timing device is operated in such a manner that current is supplied to said base via said diode by disconnecting said lead wire, and thus the alarm circuit connected to the output side of said transistor is operated.

Claim 9

An alarm system utilizing electromagnetic waves for detecting a moving object, comprising, in combination: at least one antenna means; at least one transmitter-receiver apparatus having an oscillation loop for detecting changes in the impedance of said antenna means; an amplifier circuit is operatively connected to said transmitter-receiver apparatus for amplifying an output signal from said transmitter-receiver apparatus; an alarm device operatively connected to said amplifier circuit is operated by the amplified signal so that an alarm is produced in response to said object moving in the range of space covered by the electromagnetic waves radiated from said antenna means; a timing device disposed between said amplifier circuit and said alarm device; said alarm device is operated only when the intensity and the timing of the received signal and said transmitter-receiver apparatus exceeds their specific predetermined values; and wherein said timing device includes: a transistor, a diode connected between the base of said transistor and the power source, and a lead wire connected between said power source and the ground so that the current to flow in the base of said transistor is normally cut off; and said timing device is operated in such a manner that current is supplied to said base via said diode by disconnecting said lead wire, and thus the alarm circuit connected to the output side of said transistor is operated.